SEATTLE — Karen Sykes, a well-known outdoors writer and photographer who died of hypothermia in rugged terrain in Mount Rainier National Park over the weekend was experienced, prepared and knew the mountain well after having written dozens of stories about treks through the area.

The 70-year-old hiker did not have other injuries and her death was an accident, the Pierce County medical examiner's office said Monday. Sykes had heart disease, according to an autopsy, but her daughter and others said she was healthy and fit and often hiked twice a week.

While not certain about the circumstances around her death, those who knew Sykes said earlier that they believe her death was something that could happen to anyone no matter how experienced.

“The mountains are big. There's a lot going on. She was extremely experienced but experience has nothing to do with any of it,” said Kim Brown, who has hiked with Sykes.

“She was very careful, very cautious,” Brown said of Sykes, who was prominent in the Northwest hiking community for her trail reviews and photographs and her book on hiking western Washington.

“It's just something that happens out in the mountains. Everybody who goes in the mountains knows this can happen. It doesn't mean that you shouldn't go out, you need to be aware of it.”

Sykes was reported missing late Wednesday when she failed to meet up with her boyfriend as planned during a day hike in the east side of the mountain.

“Karen knew these things and I'm sure did them. She really had her bases covered, and unfortunately accidents happen sometimes,” Ramos said. She added that Sykes would want people to know that there are some risks but “she wouldn't want to scare people from hiking.”

Mary Kay Nelson, executive director of Visit Rainier, an organization that promotes tourism at the mountain, said Sykes was researching a story that she likely would have submitted to the website.

She said Sykes had written about more than 100 hikes in the Rainier area, and “was always eager to find new places to go, hidden hikes that weren't well-traveled.”Nelson said her disappearance was particularly shocking because she was so experienced.

“It tells us that no matter how prepared we are, accidents happens and things can happen. We need to take outdoor recreation seriously. There's a certain amount of risk every day we get up, whatever we do,” she said.

Since 2000, 18 hikers have died in Mount Rainier National Park, including from falls, drowning and heart attacks, according to park statistics.Annette Shirey, 52, who lives in Tucson, Arizona, said her mother had a personal connection to the mountain and wanted to share that love with others.

"The mountains were always a place that gave her strength and was always uplifting for her,” she said. “It helped restore her spirit and her strength.”